Selecting the necessary equipment for a heating system is an extremely important task. Owners of private houses are sure to encounter this, and recently many apartment owners are striving to achieve complete independence in this matter by creating their own autonomous systems. And one of the key points, naturally, is the issue of choosing a boiler.
If your home is connected to the main natural gas supply, then there is nothing to think about - the optimal solution would be to install gas equipment. The operation of such a heating system is incomparably more economical than all others - the cost of gas is relatively low, especially in comparison with electricity. All sorts of problems with additional acquisition, transportation and storage of fuel, typical for solid or liquid fuel installations, disappear. If all installation requirements are met and the rules of use are followed, it is completely safe and has high performance indicators. The main thing is to correctly decide on the right model, for which you need to know how to choose a gas boiler so that it fully complies with the specific operating conditions and meets the wishes of the owners in terms of functionality and ease of use.
Basic parameters for choosing a gas boiler
There are a number of criteria by which you should evaluate the model of boiler you are purchasing. It should be immediately noted that almost all of them are interconnected and even interdependent with each other, so they must be considered immediately and in their entirety:
- The key parameter is the total thermal output of the gas boiler, which must correspond to the tasks of a specific heating system.
- The location of the future installation of the boiler - this criterion will very often depend on the power mentioned above.
- Boiler type according to layout - wall-mounted or floor-mounted. The choice also directly depends on both the power and the installation location.
- The type of boiler burner - open or closed - will depend on the same criteria. Accordingly, a system for removing combustion products is organized - through a conventional chimney with natural draft or through a forced smoke removal system.
- Number of circuits - will the boiler be used only for heating needs, or will it also provide hot water. If a double-circuit boiler is selected, then its type based on the structure of the heat exchangers is taken into account.
- The degree of dependence of the boiler on the energy supply. This parameter is especially important to take into account in cases where power outages in a populated area occur with alarming regularity.
- Additional equipment of the boiler with elements necessary for efficient operation of the heating system, the presence of built-in control systems and ensuring operational safety can be of great importance.
- And finally, the boiler manufacturer, and, of course, the price, which will depend on many of the factors listed above.
The first step is to correctly determine the boiler power
It is simply impossible to move on to choosing any boiler if there is no clarity about what heating installation must be in place.
The technical documentation of the boiler must indicate the value of the rated power, and in addition, recommendations are often given as to how much space it is designed to heat. However, these recommendations can be considered rather conditional, since they do not take into account the “specifics”, that is, the actual operating conditions and features of the house or apartment.
The same caution should be applied to widespread“axiom” that to heat 10 m² of housing area, 1 kW of thermal energy is needed. This value is also very approximate, which can only be valid under certain conditions - average ceiling height, one external wall with one window, etc. In addition, the climate zone, the location of the premises relative to the cardinal points and a number of other important parameters are not taken into account at all.
Thermal engineering calculations according to all the rules can only be carried out by specialists. However, we will take the liberty of offering the reader a method for independently calculating power, taking into account most of the factors influencing the efficiency of heating a house. With such a calculation, there will certainly be an error, but within completely acceptable limits.
The method is based on calculating the required thermal power for each room where heating radiators will be installed, followed by summing the values. Well, the following parameters serve as initial data:
- Room area.
- Ceiling height.
- The number of external walls, the degree of their insulation, their location relative to the cardinal points.
- Level of minimum winter temperatures for the region of residence.
- Number, size and type of windows.
- “Neighborhood” of the room vertically - for example, heated rooms, a cold attic, etc.
- The presence or absence of doors to the street or to a cold balcony.
Any owner of a house or apartment has a plan for his housing. Having placed it in front of you, it will not be difficult to create a table (in an office application or even just on a sheet of paper) that indicates all the heated rooms and their characteristic features. For example, as shown below:
| Premises: | Area, ceiling height | External walls (number where facing) | Number, type and size of windows | The presence of a door to the street or balcony | Required thermal power |
|---|---|---|---|---|---|
| TOTAL: | 92.8 m² | 13.54 kW | |||
| 1st floor, insulated floors | |||||
| Hall | 9.9 m², 3 m | alone, West | single, double-glazed window, 110×80 | No | 0.94 kW |
| Kitchen | 10.6 m, 3 m | one, South | one, wooden frame, 130×100 | No | 1.74 kW |
| Living room | 18.8 m², 3 m | three, North, East | four, double-glazed window, 110×80 | No | 2.88 kW |
| Tambour | 4.2 m², 3 m | alone, West | No | one | 0.69 kW |
| Bathroom premises | 6 m², 3 m | one, North | No | No | 0.70 kW |
| 2nd floor, above – cold attic | |||||
| Hall | 5.1 m², 3 m | one, North | No | No | 0.49 kW |
| Bedroom No. 1 | 16.5 m², 3 m | three, South, West | single, double-glazed window, 120×100 | No | 1.74 kW |
| Bedroom No. 2 | 13.2 m², 3 m | two, North, East | No | 1.63 kW | |
| Bedroom No. 3 | 17.5 m², 3 m | two, East, South | two, double-glazed window, 120×100 | one | 2.73 kW |
After the table has been compiled, you can proceed to calculations. To do this, below is a convenient calculator that will help you quickly determine the required heating power for each room.
The level of negative street temperatures is taken from the average characteristic of the coldest ten-day period of winter in the region of residence.
Reading time: 3 min
To heat residential and office premises, equipment with an electric water heater is used. To ensure a balance of temperature and energy consumption, the electric boiler is calculated. When determining operating parameters, not only the area of the rooms is taken into account, but also the physical properties of the materials of the walls, floor and ceiling of the room.
What is the power of an electric boiler
An electric boiler is a reservoir with a heat exchanger through which tap water or a special coolant with increased thermal characteristics is pumped.
The boiler is connected to a household AC network; it heats the water using heating elements or electrodes isolated from the water. The design of the equipment includes a temperature regulator.
Power consumption depends on the degree of cooling of the coolant during circulation through the heating radiators in the building. Part of the energy is spent on heat losses in the boiler design (heating the walls or protective casings of the heating elements). An information plate is installed on the external part of the equipment, which indicates the operating parameters of the product and power consumption.
Methods for determining the power of an electric boiler
Calculation of the operating power of a heating boiler is performed to ensure a balanced heating system capable of maintaining a comfortable room temperature under various external conditions.
The equipment must ensure uniform heating of the rooms; changes in wind direction should not have a negative impact on the conditions in the rooms. Before choosing equipment, the home owner needs to know how to calculate the power of an electric boiler, taking into account the characteristics of the room.
For calculations, 2 main methods are used:
- by the area of the house or rooms connected to the heating circuit and boiler;
- by volume of premises.
An auxiliary technique for determining the power of a hot water supply circuit is intended to calculate additional productivity. The resulting parameter is summed with a pre-calculated value of energy consumption for heating the house.
Then the ability of the electrical wiring connected to the building is checked to withstand the maximum load when the heating elements of the boiler are operating.
Calculation of the boiler according to the area of the house
The basic method is to determine the power of an electric heating boiler based on the area of the premises. To determine the value, the base value of the power required to heat a room of 10 m² is used.
The coefficient does not depend on the climate zone; it is roughly assumed that to warm up 10 m² it is necessary to expend 1 kW of power. The coefficient does not take into account the thermal conductivity of wall materials and the height of the room, therefore, to clarify the calculation, additional correction factors determined experimentally are used.
For example, if the ceiling height is more than 2.7 m, an additional correction parameter is introduced equal to the ratio of the actual height to the value of 2.7 m. The climate coefficient depends on the location of the house, the value ranges from 0.7 for the southern regions to 2.0 - northern regions. If the heating unit is also used for hot water supply, then a power reserve of 25-30% is added to the resulting indicator.
There is another way to calculate based on the formula S*K*100, where parameter S is the area of the premises, and K is the heat loss coefficient, varying depending on the minimum air temperature threshold. The base value is 0.7, used in areas with a minimum temperature of -10°C. For every 5°C decrease in climate norm, the coefficient increases by 0.2.
The method is not used when calculating a boiler for premises with the following design features:
- Availability of plastic or wooden windows with double glazing.
- Use of an additional thermal insulation layer with a thickness of 150 mm, located inside or outside a brick wall (2 brick sizes thick).
- Preservation of an unheated attic space and the absence of thermal insulation material on the roof trim.
- Increasing the height of living rooms to 2.7 m or more.
Calculation of boiler power by volume
Calculation of the power of an electric heating boiler for the volume of residential premises is based on the heat loss coefficient, which is:
- From 0.6 to 0.9 - for brick buildings with improved thermal insulation. The house uses plastic 2-chamber windows; a roof made of heat-insulating material can be used.
- From 1 to 1.9 - for buildings built of brick (double masonry), with a standard roof and wooden windows.
- From 2 to 2.9 - for rooms with poor thermal insulation (for example, with walls 1 brick thick).
- From 3 to 4 - for buildings built of wood or made of corrugated metal sheet with a layer of heat-insulating material.
When calculating, a formula of the form is used V*K*T/860, which takes into account the volume of the house V, the correction factor K and the difference in temperature inside the house and outside the room. For the calculation, the minimum air temperature characteristic of the location of the house is taken.
The obtained value is excessive, but in the event of prolonged frosts it will be possible to maintain the temperature in the house within the specified parameters. The given method for calculating the power of an electric boiler for heating a house does not take into account the supply of additional warm liquid for washing dishes or showers.
For residential premises in panel or brick houses, calculations are carried out according to SNiP standards. The rules set the required power to heat 1 m³ of air within 41 and 34 W (for a house made of panels and sand-lime brick, respectively).
Then the owner of the premises takes measurements of the height and area, and a safety margin of 10% is added to the resulting value (in case the air temperature drops in winter). When installing energy-saving windows, it is allowed to install a boiler with a power less than the calculated one.
For corner rooms, the number of walls in contact with the street is taken into account. If only 1 wall faces the outside of the house, then a coefficient of 1.1 must be applied. Each additional wall increases the value of the correction parameter by 0.1. To reduce heat losses, it is recommended to analyze the room with a special device and then install an insulator layer.
Calculation for DHW
The calculation of an electric boiler for heating a private house, which is also used for hot water supply, takes into account the following factors:
- The amount and temperature of warm water necessary to ensure the life of people living in the room.
- Based on the first parameter, the volume of hot water +90°C is determined, which is then diluted with a flow of cold liquid to produce warm water.
- Based on the obtained value, the electric boiler is calculated. When determining the parameters, the decrease in tap water temperature in winter is not taken into account.
For example, a residential building consumes 200 liters of warm water (Vg) heated to +40°C (Tg) every day. It is assumed that the required temperature is obtained by mixing hot and cold water. The owner plans to purchase a boiler that heats the liquid to +95°C (Tk), water is supplied to the cold water supply line at a temperature of +10°C (Tx).
The volume of hot water is determined by the formula Vg*(Tg-Tx)/(Tk-Tx)=200*(40-10)/(95-10). The calculation shows that to ensure the supply of hot water per day, it is necessary to heat 71 liters of liquid to a temperature of +95°C.
Further calculations are based on the coefficient of specific heat capacity of water (4.218 kJ per kg when heated by 1°C), the weight of the liquid and the temperature difference. The resulting value is then converted into kilowatts according to the tables; it is recommended to round the parameter upward.
For the situation described above, an additional power of about 5 kW is required. The obtained value implies heating the water in 1 hour; if the liquid is used evenly throughout the day, then it is possible to reduce additional energy costs by 2 times.
These are mobile boiler units designed to provide heat and hot water to both residential and industrial facilities. All equipment is placed in one or several blocks, which are then joined together, resistant to fires and temperature changes. Before choosing this type of energy supply, it is necessary to correctly calculate the power of the boiler room.
Block-modular boiler houses are divided according to the type of fuel used and can be solid fuel, gas, liquid fuel and combined.
For a comfortable stay at home, in the office or at work during the cold season, you need to take care of a good and reliable heating system for the building or premises. To correctly calculate the thermal power of a boiler room, you need to pay attention to several factors and parameters of the building.
Buildings are designed in such a way as to minimize heat loss. But taking into account timely wear and tear or technological violations during the construction process, the building may have vulnerable spots through which heat will escape. To take this parameter into account in the overall calculation of the power of a modular boiler room, you need to either get rid of heat loss or include it in the calculation.
To eliminate heat loss, you need to conduct a special study, for example, using a thermal imager. It will show all the places through which heat leaks and those that need insulation or sealing. If it was decided not to eliminate heat loss, then when calculating the power of a modular boiler room, you need to add 10 percent to the resulting power to cover heat loss. Also, when calculating, it is necessary to take into account the degree of insulation of the building and the number and size of windows and large gates. If there are large gates for trucks to enter, for example, about 30% of the power is added to cover heat loss.
Calculation by area
The easiest way to find out the required heat consumption is to calculate the power of the boiler room based on the area of the building. Over the years, experts have already calculated standard constants for some indoor heat transfer parameters. So, on average, to heat 10 square meters of area you need to spend 1 kW of thermal energy. These figures will be relevant for buildings built in compliance with heat loss technologies and a ceiling height of no more than 2.7 m. Now, based on the total area of the building, you can obtain the required boiler room power.
Calculation by volume
Calculating the power of the boiler room by the volume of the building is considered more accurate than the previous method of calculating power. Here you can immediately take into account the height of the ceilings. According to SNiPs, heating 1 cubic meter in a brick building requires an average of 34 W. In our company, we use various formulas to calculate the required thermal power, taking into account the degree of insulation of the building and its location, as well as the required temperature inside the building.
What else needs to be taken into account when calculating?
To fully calculate the power of a block-model boiler house, it will be necessary to take into account several more important factors. One of them is hot water supply. To calculate it, it is necessary to take into account how much water will be consumed daily by all family members or production. Thus, knowing the amount of water consumed, the required temperature and taking into account the time of year, you can calculate the correct power of the boiler room. It is generally customary to add about 20% to the resulting figure for heating the water.
A very important parameter is the placement of the heated object. To use geographic data in calculations, you need to refer to SNiPs, in which you can find a map of average temperatures for the summer and winter periods. Depending on the placement, the appropriate coefficient must be applied. For example, for central Russia the relevant figure is 1. But the northern part of the country already has a coefficient of 1.5-2. So, having received a certain figure during past research, you need to multiply the resulting power by a coefficient, as a result the final power for the current region will become known.
Now, before calculating the power of the boiler room for a particular house, you need to collect as much data as possible. There is a house in the Syktyvkar region, built of brick, using technology and all measures to avoid heat loss, with an area of 100 square meters. m. and a ceiling height of 3 m. Thus, the total volume of the building will be 300 meters per cube. Since the house is brick, you need to multiply this figure by 34 W. This turns out to be 10.2 kW.
Taking into account the northern region, frequent winds and short summers, the resulting power needs to be multiplied by 2. Now it turns out that 20.4 kW needs to be spent for comfortable living or work. It is necessary to take into account that some part of the power will be used to heat the water, and this is at least 20%. But for a reserve it is better to take 25% and multiply by the current required power. The result is a figure of 25.5. But for reliable and stable operation of the boiler installation, you still need to take a reserve of 10 percent so that it does not have to work for wear and tear in a constant mode. The total is 28 kW.
In this simple way, the power required for heating and water heating was obtained, and now you can safely choose block-modular boiler houses, the power of which corresponds to the figure obtained in the calculations.
One of the first parameters that people pay attention to when selecting heating equipment is performance. Calculation of the power of a gas heating boiler is performed in several ways. Comfort during operation depends on accurate calculations.
How to choose the power of a gas boiler
Calculation of the power of a gas heating boiler based on area is carried out in three different ways:
European manufacturers often calculate the performance of boiler equipment based on the volume of the room. Therefore, the technical documentation indicates the possibility of heating in m³. This factor is taken into account when choosing a unit manufactured in EU countries.
Most consultants selling heating equipment independently calculate the required performance using the formula 1 kW = 10 m². Additional calculations are made based on the amount of coolant in the heating system.
Calculation of a single-circuit heating boiler
As noted above, independent calculations of the operating parameters of heating equipment are performed according to the formula 1 kW = 10 m². To the obtained result, 15-20% of the reserve is added, due to which the heat generator, even in severe frosts, does not operate at full load, which extends its service life.- For 60 m², a unit of 6 kW + 20% = 7.5 kilowatts. If there is no model with a suitable performance size, preference is given to heating equipment with a higher power value.
- Calculations are carried out in a similar way for 100 m² - the required power of the boiler equipment is 12 kW.
- To heat 150 m² you need a gas boiler with a capacity 15 kW + 20% (3 kilowatts) = 18 kW. Accordingly, for 200 m², a 22 kW boiler is required.
How to calculate the power of a double-circuit boiler
The formula for calculating the required power of a double-circuit gas boiler based on the heating area and hot water supply points is as follows: 10 m² = 1 kW +20% (power reserve) + 20% (for water heating). It turns out that 40% is immediately added to the calculated productivity.The power of a double-circuit gas boiler for heating and hot water heating for 250 m² will be 25 kW + 40% (10 kilowatts) = 35 kW. The calculations are suitable for dual-circuit equipment. To calculate the performance of a single-circuit unit connected to an indirect heating boiler, a different formula is used.
Calculation of the power of an indirect heating boiler and a single-circuit boiler
To calculate the required power of a single-circuit gas boiler with an indirect heating boiler, you must perform the following steps:- Determine what volume of the boiler will be sufficient to meet the needs of the residents of the house.
- The technical documentation for the storage tank indicates the required performance of the boiler equipment to maintain hot water heating, without taking into account the required heat for heating. A 200 liter boiler will require about 30 kW on average.
- The productivity of the boiler equipment required to heat the house is calculated.
The resulting numbers are added up. An amount equal to 20% is subtracted from the result. This must be done for the reason that the heating will not work simultaneously for heating and hot water supply. The calculation of the thermal power of a single-circuit heating boiler, taking into account an external water heater for hot water supply, is done taking into account this feature.
What power reserve should a gas boiler have?
The performance reserve is calculated depending on the configuration of the heating equipment:- For single-circuit models, the margin is about 20%.
- For dual-circuit units, 20%+20%.
- Boilers with connection to an indirect heating boiler - in the storage tank configuration, the required additional performance reserve is indicated.
Calculation of gas demand based on boiler power
The formula for calculating gas consumption, depending on the power of the boiler used, takes into account the efficiency of the heating equipment. For standard models of classic heating heat generators, the efficiency will be 92%, for condensing heat generators up to 108%.In practice, this means that 1 m³ of gas is equal to 10 kW of thermal energy, subject to 100% heat transfer. Accordingly, with an efficiency of 92%, fuel consumption will be 1.12 m³, and with 108% no more than 0.92 m³.
The method for calculating the volume of gas consumed takes into account the performance of the unit. So, a 10 kW heating device will burn 1.12 m³ of fuel within an hour, a 40 kW unit will burn 4.48 m³. This dependence of gas consumption on the power of boiler equipment is taken into account in complex thermal calculations.
The ratio is also included in online heating costs. Manufacturers often indicate average gas consumption for each model produced.
To fully calculate the approximate material costs of heating, you will need to calculate the electricity consumption in volatile heating boilers. At the moment, boiler equipment operating on main gas is the most economical heating method.
For large heated buildings, calculations are carried out exclusively after an audit of the building’s heat loss. In other cases, special formulas or online services are used for calculations.
When choosing a boiler, it is sometimes difficult to determine its compliance with the heating requirements of a particular home. There seems to be data on dimensions and internal volume. But this turns out to be not enough. The modern definition requires knowledge of the heat loss rate characteristic of this house. It is with heat losses that the possibility of choosing the power of the future boiler is associated, which must compensate for them during its operation.
Incorrectly selected boiler power leads to additional fuel costs(gas, solid and liquid). Each option will be discussed below, but for now you need to take into account that, as a first approximation, insufficient boiler power leads to a low temperature in the heating system due to its slow and insufficient heating. Power that exceeds the required results in the system operating in pulse mode. It causes sharp increase in gas consumption, wear of the gas valve. Reducing heating costs can be achieved by choosing the correct boiler power and calculating the heating system.
Method for calculating heat losses
Calculation of heat losses is carried out according to certain techniques differing from the climatic zone of the country. Having such calculations in hand, it is much easier to navigate the choice of all devices of the future heating system. The abundance of incoming data, basic and auxiliary, as well as the formalization of calculations, made it possible to introduce automation and carry them out using computer programs. Thanks to this, such calculations have become available for individual execution on the websites of construction companies.
Of course, only a specialist can determine the exact results. But independent determination of the amount of heat loss will give quite visible results with the determination of the required power. By entering the data requested by the program, according to house parameters(cubic capacity, materials, insulation, windows and doors, etc.), after performing the proposed actions, the value of heat losses is obtained. The resulting accuracy is sufficient to determine the required boiler power.
Using house odds
The old way of determining the amount of heat loss was use of house coefficients of 3 types for individual calculation of the power of a gas boiler using a simplified method:
- from 130 to 200 W/m2 - houses without thermal insulation;
- from 90 to 110 W/m2 - houses with thermal insulation, 20−30 years;
- from 50 to 70 W/m2 - thermally insulated house with new windows, 21st century.
Knowing the value of your coefficient and the area of the house, the desired value is obtained by multiplication. The required power was determined even more simply during Soviet times. Then it was believed that 10 kW per 100 meters of area was just right.
However, today such accuracy is no longer enough.
What does boiler power affect?
If it is too small, then a powerful solid fuel boiler will not “burn out” the remaining fuel due to lack of air supply, The chimney will quickly become clogged, and fuel consumption will be excessive. Gas or liquid fuel boilers will quickly heat a small amount of water and turn off the burners. This burning time will be shorter, the more powerful the boilers. In such a short time, the removed combustion products will not have time to warm up the chimney, and condensation will accumulate there. Acids formed quickly will fall into disrepair like a chimney, and the boiler itself.
Long burner operating time allows the chimney to warm up and the condensation will disappear. Frequent switching on of the boiler leads to wear and tear on the boiler and the chimney, as well as increased fuel consumption due to the need to heat up the chimney duct and the boiler itself. To calculate the power of a liquid fuel (diesel) boiler, you can use calculator program, taking into account many of the features described above (structures, materials, windows, insulation), but express analysis can be carried out using the given methodology.
It is believed that to heat 10 square meters of house area you need 1-1.5 kW of boiler power. DHW in a house with high-quality insulation, without heat loss, and an area of 100 square meters is not taken into account. m. Coefficients for the level of insulation used to calculate the required power of the ZhT boiler:
- 0,11 - apartment, 1st and last floors of an apartment building;
- 0,065 - apartment in an apartment building;
- 0,15 (0,16) - private house, wall 1.5 bricks, without insulation;
- 0,07 (0,08) - private house, wall 2 bricks, 1 layer of insulation.
For calculation, the area is 100 sq. m. is multiplied by a factor of 0.07 (0.08). The resulting power is 70-80 W per 1 sq. m. area. The boiler power is reserved by 10−20%, for DHW the reserve increases to 50%. This calculation is very approximate.
Knowing the heat losses, we can say about the required amount of heat generated. Typically, comfort in the home is taken to mean +20 degrees Celsius. Since there is a period of minimum temperatures throughout the year, the need for heat increases sharply on these days. Taking into account periods when temperatures fluctuate around winter averages, the boiler power can be taken equal to half of the previously obtained value. In this case, the calculation includes compensation for heat losses from other heat sources.
Solving the problem of excess power
In case of low heat demand, the boiler power becomes obviously high. There are several solutions. Firstly, the use of 4-way mixing valves in hydraulic systems is proposed during this period. Can be applied thermohydraulic distributor. This allows you to regulate water heating without changing the boiler power, due to valves and circulation pumps. This ensures optimal boiler operation.
Due to the high cost of the method, a budget option is being considered multi-stage burners in inexpensive gas and HT boilers. With the onset of the specified period, a stepwise transition to reduced combustion reduces the boiler power. An option for a smooth transition is modulation or smooth adjustment, commonly used in wall-mounted gas appliances. This possibility is almost never used in the designs of HT boilers, although a modulating burner is a more advanced option than a mixing valve. Modern pellet boilers are already equipped power control system and automatic fuel supply.
For the inexperienced consumer presence of a modulation burner system may seem like a sufficient reason to refuse to calculate the heat losses of a house, or at least limit ourselves to their approximate determination. By no means, the presence of such a function cannot solve all the problems that arise: if, when the boiler is turned on, it starts working at maximum power, then after a while the automatic machine reduces it to the optimum.
At the same time, a powerful boiler in a small system manages to heat the water and switch off Even before the transition of the modulating burner, I had the desired level of combustion. The water cools down quickly enough, the situation will repeat itself “until a blot”. As a result, the boiler operates in pulses as with a single-stage powerful burner. The change in power can reach no more than 30%, which will ultimately lead to failures with a further increase in external temperature. It is worth remembering that we are talking about relatively cheap devices.
In more expensive condensing-type boilers, the modulation limits are wider. ZhT boilers can cause tangible difficulties when trying to use it in small and well-insulated houses. In such a house, about 150 sq. m, 10 kW of power is enough to cover heat losses. In the line of ZhT boilers offered by manufacturers, the minimum power is twice as large. And here an attempt to use such a boiler can lead to a situation even worse than the one described above.
Diesel fuel (diesel fuel) is burning in the firebox; everyone has seen the black plume behind the unheated and unregulated diesel engine. And here soot falls out abundantly in the products of incomplete combustion; it and the unburned products are completely clog the combustion chamber. And now the brand new boiler urgently needs to be cleaned so as not to reduce efficiency and heat exchange must be restored. And after all, if you had first selected the correct boiler power, all the problems described would not have arisen.
In practice, you should choose a boiler power slightly lower than the heat loss of the house. Boilers with COGVS, i.e. double-circuit, heating water for heating and hot water supply, have gained popularity and practical use. And among these two functions, the required power for central heating is less than for domestic hot water. Of course, this approach made choosing the boiler power more difficult.
Method for producing hot water in a 2-circuit boiler - flow heating. Since the contact (heating) time of running water is insignificant, the power of the boiler heater must be high. Even with low-power double-circuit boilers, the hot water system has 18 kW of power and this is only the minimum, which makes it possible to take a normal shower. The presence of a modulation burner in such a device will make it possible to work with a minimum power of 6 kW, almost equal to the heat losses in a 100-meter house with high-quality thermal insulation.
In real life, the average needs for a heating season will be no more than 3 kW. That is, although the situation is not ideal, it is acceptable. A way to reduce the required power of a DHW system is to use a storage tank for DHW. And this is very similar to a single-circuit boiler equipped with a boiler. The boiler connected through a heat exchanger to the boiler has a capacity not less than 100 liters. This is a minimum designed for several water points and their simultaneous use.
This scheme allows reduce boiler power, combined with a water heater. As a result, the task is completed and the boiler power is sufficient to compensate for heat losses (CH) and DHW (boiler). At first glance, as a result, while the boiler is running, hot water will not flow into the heating system and the temperature in the house will drop. In fact, for this to happen, the boiler must turn off for 3 - 4 hours. The process of replacing heated water from the boiler with cold water occurs gradually. The practice of using heated water says that even draining half the volume, which is 50 liters at a temperature of about 85 degrees Celsius and the same amount of cold water to use, leads to the remainder in the tank of half the volume hot and the same amount cold. The heating time will be no more than 25 minutes. Since such a volume is not consumed in a family at one time, the heating time of the boiler will be significantly shorter.
An example of determining boiler power
An approximate method for determining the power of a gas boiler based on its specific power (Rud) per 10 square meters. m and taking into account the conditions of climatic zones, heated area - P.
- 0.7−0.9 - south;
- 1.2−1.5 kW - middle band;
- 1.5−2.0 kW - north
Boiler power is determined Rk = (P*Rud)/10; where Rud = 1;
Volume of water in the system Osist = Pk*15; where 1 kW is taken for 15 liters of water
So for the house from the example with an HT boiler, in the north, the calculation will look like this:
Pk = 100*2/10 = 20 (kW);
